The longest interval between mounts decreased (P < 0.007) when the number of cows in estrus at one time increased from 1 (5.3 ± 0.7 h) to ≥7 (2.6 ± 0.3 h; Figure 3). The longest interval between mounts was not different (P > 0.13) when 2 to 6 cows were in estrus simultaneously, compared with 1 cow in estrus. The greatest average interval between mounts was longer during the second half of estrus (3.9 ± 0.2 h; P = 0.05) compared with the first half (3.1 ± 0.3 h).